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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" type="text/css" href="6.css">
    <link rel="stylesheet" type="text/css" href="id.css">
    <style type="text/css">
        p {
            color: green;
            background-color: brown;
        }
    </style>
</head>

<body>
    <h1 style="color:blue">blue</h1>
    <!--inline-->
    <p>green</p>
    <h2>yellow</h2>
    <h3 id="para1">id</h3>
    <h3 class="para2">class</h3>
    <h3 class="para2 para3 para4">class</h3>
    <h3 id="para1" class="para2">id+class</h3>
    <h3 id="para5">para5</h3>
    <h3 style="text-decoration: underline">underline</h3>
</body>

</html>